One type of transportation system that propels a car with a closed loop cable is a mountain gondola. The cable in that system is continuously driven in one direction by a motor, and the motor is located at one end of the system. The gondola car that the passengers ride in is suspended from the cables, and the cables provide all vertical, horizontal and directional guidance and support to the car. The gondola system has a unique characteristic, mainly a result of the continuously moving cable: the car has to be disconnected from the cable and decelerated as it arrives at a terminal, so that the passengers can enter and leave the car. Furthermore, the car must be accelerated from a stop to the speed of the cable, then attached to it to put the car in the system. As with any other system having a continuously moving cable, the gondola system consequently contains complex, costly coupling equipment to couple and decouple the car and the cable and accelerate and decelerate the car. Generally speaking, this equipment includes an auxiliary drive of some sort containing a series of wheels that engage the car to accelerate it to a speed of the cable, and coupling equipment to connect the car to the cable once that speed is reached to provide smooth acceleration from a stop. Stopping the car involves roughly the same sequence, but in reverse: the car is detached from the cable and rides on rollers that slowly decelerate it to a stop.
In another related system passengers move in cars in a guideway. The cars are propelled back and forth in the guideway. They are connected to the same cable, and the cable passes around the guideway and is moved or pulled back and forth by a motor at one end of the guideway. As a result, the cars move synchronously (always move at the same time) in opposite directions, slowing down the system by making it impossible to individually control the cars.